Welcome to the forum!
Yep, as Geno says, more often than not this is due to lower quality media or burning at too high a speed.
What brand of discs do you use and what speed did you burn at?
I don't know if you have a Staples or PC World anywhere close, but they often have Verbatim DVD media on offer (either at a lower price, or if you're really lucky, BOGOF ).
The Asda nearest me has recently started stocking Verbie CD-Rs, so hopefully sometime in the near future they may stock Verbie DVD Rs.
I didn't look too closely when I was whizzing around Tesco's on Friday, but IIRC they might stock Verbatim as well.